How to remove comment completely?

Appearance>Editor>Comments (comments.php)

Delete:

<?php // You can start editing here -- including this comment!
	if ( have_comments() ): ?>
		<div id="comments">
            <h2 id="comments-title">
                <?php comments_number(__( 'No Comments', 'simplecatch' ), __( '1 Comment', 'simplecatch' ), __( '% Comments', 'simplecatch' ) );?>
            </h2><!-- #comments -->

            <div class="navigation clearfix">
                <div class="alignleft">
                    <?php previous_comments_link();?>
                </div>
                <div class="alignright">
                    <?php next_comments_link(); ?>
                </div>
            </div> <!-- .navigation -->

            <ul class="commentlist">
                <?php wp_list_comments();?>
            </ul>

             <div class="navigation clearfix">
                <div class="alignleft">
                    <?php previous_comments_link();?>
                </div>
                <div class="alignright">
                    <?php next_comments_link(); ?>
                </div>
            </div> <!-- .navigation -->

     	</div><!-- .comment-wrap -->
	<?php else: // this is displayed if there are no comments so far

		if (comments_open()): // If comments are open, but there are no comments.

		else: // comments are closed ?>
           <p class="nocomments"><?php _e( 'Comments are closed.', 'simplecatch' );?></p>
    	<?php endif; 

	endif;?>

 	<?php
	if (comments_open()): // The comment form 

		$req = get_option( 'require_name_email' );
	    $aria_req = ( $req ? " aria-required='true'" : '' );
		$fields =  array(
			'author'	=>	'<label>Name</label><input type="text" class="text" placeholder="'.esc_attr( 'Name ( required )' ).'" name="author"'. $aria_req .' />',
			'email' 	=>  '<label>Email </label><input type="text" class="text" placeholder="'.esc_attr( 'Email ( required )' ).'" name="email"'. $aria_req .' />',
			'url'    	=>	 '<label>Website </label><input type="text" class="text" placeholder="'.esc_attr( 'Website' ).'" name="subject"'. $aria_req .' />'
		);

		$args = array(
			'title_reply'          => 	__( 'Leave a Comment', 'simplecatch' ),
			'comment_notes_before' =>	 '',
			'comment_field'        => 	'<label>Comment</label><textarea name="comment" id="comment" rows="10" tabindex="4"></textarea>',
			'label_submit'         =>	 __( 'Submit','simplecatch' ),
			'comment_notes_after'  => 	'',
			'fields'               => 	apply_filters( 'comment_form_default_fields', $fields )
			 );

		comment_form($args);
	endif; // if you delete this the sky will fall on your head ?>

Do you want to globally disable comments?

Check out this plugin.

Individually on posts and pages, in the discussion box you can disable them for that one post/page.

i have tried this plugin, but my comment still showed up. my website is https://www.ntpenergysolutions.com/.

Do you have Pages, Posts and Media all checked in the Disable Comments settings?